Buick LeSabre 1965 Service Manual page 623

ELECTRICAL SYSTEMS SIGNAL SYSTEMS 1 0 - 5 3
SECTION 10-G
SIGNAL SYSTEMS
CONTENTS OF SECTION 10-G
Paragraph Subject
10-45 Horns and Control Circuit
10-46 Trouble Diagnosis and
Adjustment of Horns
Page
it 10-53
10-53
Paragraph
10-47
Subject
Direction Signal Lamps
Page
. . . 10-55
10-45 HORNS AND
CONTROL CIRCUIT
a. Horns and Relay
Two Delco-Remy electrically op-
erated vibrator type horns are
mounted in the engine compart-
ment. Both horns are operated
simultaneously by a horn relay
which is controlled by the horn
push button on the steering wheel.
One horn is high pitched and the
other is low pitched, so that to-
gether they produce a pleasant
blended tone.
The horn relay is an electrical
switch which closes the circuit
between the battery and the horns
when the push button is pressed
and opens the circuit when the
button is released. The relay
permits control of the horns with
a small amount of current passing
through the horn button contacts.
The high current required by the
horns would cause arcing and
burning of these contacts.
When the horn button contacts are
closed, a small amount of current
flows through the relay winding
to ground at the horn push button
contact. This magnetizes the re-
lay core which attracts the flat
steel relay armature. The arm-
ature has a contact point which
makes contact with a stationary
point to close the horn circuit.
When horn push button is re-
leased, current s t o p s flowing
through relay winding so that the
core loses its magnetism; the
armature spring then causes con-
tact points to be separated.
b. Horn Relay Ground
Circuit
The steering wheel has an ac-
tuator bar mounted across the
steering wheel. Fastened to the
base of the actuator bar, but in-
sulated from it, is a contact plate
which is "hot" at all times. See
Figure 10-55. When the actuator
bar is rocked, the contact plate
contacts a ground plate on the
steel hub of the steering wheel
to ground the horn relay winding,
close the relay contacts, and blow
the horn. When the actuator bar
is released, two springs move the
actuator bar and contact plate
assembly clear of the ground
plate.
Current is supplied to the contact
plate by a spring-loaded brush
which rides on the contact ring
located at the upper end of the
steering column. A wire attached
to the contact ring runs down in-
side the steering column jacket
and out under the instrument pan-
el. The wire from the horn relay
connects at this point.
10-46 TROUBLE DIAG-
NOSIS AND
ADJUSTMENT
OF HORNS
If a horn button contact is con-
stantly grounded, the horns will
not stop blowing or if a contact
cannot be grounded, the horns
will not blow.
There are two basic troubles,
which may be caused by a de-
fective horn relay. If neither horn
will blow at all, this trouble may
be caused by the relay points
not making contact. Or if horns
will not stop blowing, this trouble
may be caused by relay points
sticking.
a. Horns Will Not Blow
When horns, fail to blow, first
check wiring circuit and relay
because even a faulty horn will
generally make some sort of
noise if current is getting to it.
If horns are at fault, or tone is
poor, adjust each horn for spec-
ified current draw as instructed
in subparagraph e.
1. Break circuit at connector for
horn wire that enters steering
mast jacket (tan wire) and ground
wire from horn relay. If horn
now blows, horn relay ground cir-
cuit in mast jacket or steering
wheel has an open. Reconnect
wire on connector and check horn
wire and horn contacts. Circuit
from connector at mast jacket
to contact on steering wheel must
be complete. To remove horn
contact, remove two retaining
screws from actuator bar cap.
Remove four clutch-head retain-
ing screws from actuator bar.
Remove four plastic retaining
rivets from actuator plate.
2. To remove h o r n connector
brush, remove actuator bar cap.
Remove actuator bar. Lift ground
plate and horn connector brush
from steering wheel. If steering
wheel must be removed, see Fig-
ure 10-55.